Such a transport unit for sheet-metal parts is known from DE 202 16 013 U1. It is designed as a press transfer system, with which sheet-metal parts are transported between adjacent sheet-metal presses of a press working line. The transport unit has a multiaxle robot with a gripping tool. The gripping tool is arranged at the end at an extension arm flanged nonrotatably to the robot hand can be rotated via a connecting rod about a vertical axis at the end of the extension arm as needed. The robot can grip into the presses with the pivotable extension arm and pick up or discharge sheet-metal parts there, wherein the robot hand can remain outside of the press. When the workpiece is transported between the presses, the workpiece can be rotated at the end of the extension arm. The robot performs lifting movements and horizontal pivoting movements during the transport of the workpiece and transports the workpiece to a curved track.
Other press transfer systems, which have a transfer means arranged above the workpiece transport plane in the free space between adjacent presses, are known from practice. This consists of a feed cart, which is movable linearly and transversely to the press working line, with a lifting column, at the end of which is arranged a three-part telescopic carriage, which can be extended linearly on both sides, which has at the latter telescopic carriage a movable transport cart with a pivot means for a tool holder of a gripping tool. The telescopic carriage can be raised and lowered with the lifting cable at the feed cart. The kinematics of this press transfer system is limited and brings about the complicated telescopic carriage arrangement. It is necessary, on the one hand, for achieving a great extension length for meshing with the presses on both sides and, on the other hand, for forming a small telescopic carriage width in the brought-together central position for problem-free placing in the free space between the presses.